Stabilization of photographic sensitive materials



UNITED STATES PATENT OFF-ICE STABILIZATION or PHOTOGRAPHIO SEN- Y SITIVE MATERIALS John David Kendall, Ilford, England, assignor to Ilford Limited, Ilford, Essex, England, a British company No Drawing. Application October 27, 1937, Serial This invention relatesto a method of stabilizing photographic emulsions.

As is known, photographic emulsions are relatively delicate and on storage under unfavour- In Great Britain November 7, 6 Claims. (c1. 95-7 tution derivatives, their tautomeric compounds and salts of such compounds also have a very beneficial eflect in stabilizing photographic emulsions.

5 able conditions may deteriorate quickly. Accordingly this invention comprises a method 5 The deterioration may take several forms, such of stabilizing photographic materials which inas discolouration of the emulsion, a decrease in clude a light sensitive silver halide gelatine its sensitivity to light, marked increase in the emulsion consisting in treating the said material amount of chemical fog produced on development 'with a compound comprising 2-amino-4-hyof the emulsion or undesirable changes of. grada-, droxy-pyrimidine or one of its alkyl, aryl, aralkyl 0 tion of the final image. or arylene substitution derivatives or one of their Heretofore many compounds of different types tautomeric compounds or one of their salts. If have been suggested as additions to photographic a salt is employed it may be salt of either taumaterials for the purpose of rendering them less tomeric form, and whilst in general it is prefer- 5 liable to deterioration and alterations of propable to-employ the alkali metal salts on account elties and q y 011 St0rage,'With0ut impairing of their solubility other salts such as the silver their normal photographic qualities; such addisalts may be used.

t o s n lu qu quinidine, Secondary or Examples of substitution derivatives of 2- tertiary aromatic or aromatic aliphatic amines amino-i-hydroxy-pyrimidine which may be em- I g and thio-pyrazolones, also imidazoles and simiployed are as follows: i

lar compounds which form silver salts whose s'olubility does not exceed that of silver chloride. 6 methyl 2 mm 4 hydroxy pynmldme In the specification of my pending application fi Serial No. 63,451, filed February 11, 1936, I have In I :5 described a method of stabilizing photographic materials by treatment of the maternal with a 2- thiol-4-hydroxy-tpyrimidine or its alkyl, varyl or I N aralkyl substitution derivatives or a tautomeric benzoylene guanidino'(Q-amino-l-hydroxy-Bzfi-benzpyrimidinc) compound or an alkali metal or ammonium salt thereof. K\ Such, compounds areG-membered ring compounds of the following general formula:- NHz 0:011 r? M Rr-C \-N 2 amino-4-hydroxy-5-bcnzyl-6-methyl-pyrimidine Iii-( ts H c on N// Gem-(f \N where R1 and R2 may be alkyl, aryl or aralkyl OHar-NH: groups or parts of an arylene group. The utility K 40 of such compounds is believed to be due to the 1 40 presence f t t 2-aminM-hydroxy-(i-phcnyl-pynmIdIno c on I3 SH on c-NH, 45 It has now been found that-the fi-membered v compounds containing-the following sys- The compounqs may be incorporated in the I emulsion, .or they may be incorporated in the supi -'port, or in an intermediate layer between the "E sensitive emulsion and the support, such as the 50 y I NHI H baryta coating commonly employed in photothat is, 2 amino Lhydroxymyrhnidme graphic papers, or they may be incorporated in v a further protective layer coated on theemulsionf g surface, or the otherwise finished pfidfiog'raphic 55' HO N material may be bathed in a solution of the com- -H( l o-mm Pound.

Again the wrapping materials and the like which may come into contact with the photoand its alkyl,. aryl, aralkyl and-arylene substiphic material may lso en fi -Wi h he 60 It is found that photographic materials treated in accordance with this invention show marked improvement in keeping properties particularly with regard to the reduction in the tendency to form chemical fog on development and the maintenance of speed on storage and the qualities 0 the materials remain more constant.

Photographic materials treated according to the present invention also show improvement in the depth of blacks produced on development.

The compounds may conveniently be added to the silver halide emulsion just prior to coating in the proportion of about 1 to 10 cos. of a 1% solution per pound of emulsion.

The following examples illustrate the manner in which the invention may be carried into effectand they also show the results obtained by treating the photographic materials.

Exlmru: I

Three sets of photographicpaper A, B and C- were made up by coating with a normal washed bromide emulsion. The samples A were made with a normal washed bromide emulsion without any addition, the samples B with the same emul-" sion and with the addition of 1 cc. of a. 10% aqueous solution of 2-amino-4-hydroxy-pyrimidine per pound of emulsion the addition being made just prior to coating, and the samples C with the same bromide emulsion and with the addition of 10 cos. of a 10% aqueous solution of 2-amino-4- hydroxy-pyrimidine per pound of emulsion, again the addition being made just prior to the coating.

Three samples from each set were developed without exposure and under similar conditions in a standard metol hydroquin'one developer as normally used for bromide emulsions, one sample from each set being developed for two minutes at 80 F. another for four minutes at 65 F. and the third for two minutes at 65 F. The samples were then examined in a standard reflection densitometer and the fog densities or amount of blacken T incubated for 10 days at a temperature of 115 F.

The results of these tests are given in the following table:

Table 1 Amount of 10% aqueous solution of 2- Fog of Fog of Sample amino-i-hy- Time and tempemunincuincudroxy-pyriture of development bated bated. midine per sample sample lb. of emulsion 2 mins. at a) F 0.01 r n 0. 23 r n 0. 01 r n 0. 07 dn 0. 01 do 0. 03 4 mins. at F None do 0. 13 d None do 0. 07 do 0. 01 do 0. (B 2 mins. at 65 F"--- None do 0. 04 do None 0 0. (B n 0. 01 n 0. 01

2,173,628 compounds, either by incorporation or bathing.

. Emu: n

Similar sets of samples D, E and F to those described in Example I were prepared. A normal washed bromide emulsion was employed and a 10% solution of 6-methyl-2-amino-4-hydroxy- 5 pyrimidine (described in Beilstein, Volume I, 1893 edition, page 1348, under the name of iminomethyl-uracil) A standard metol hydroquinone developer was employed, and the same conditions of developl0 ment as regards times and temperatures and similar conditions of incubation of some of the samples were observed as in Example I.

The results of the examination of the developed samples with the standard reflection densitoml5 eter are given below in Table 2. Y

Table 2 Amount of 20 S0 11 ion 0 methyl-2 Time and tem ra- 'r; Fog of Sample amino-it f d 1 W t g d g a hydroxy ureo eve opmen cu ate ate pyrimidine sample sample per lb. of emulsion 25 Cubic centimeters None 2 mins. at 80 F. 0.01

None

I claim:

l. Aphotographic material having a fog inhibiting compound selected from the group consisting of 2-amino-4-hydroxy-pyrl midine, the alkyl, aryl, aralkyl and arylene substituted 2-amino 4- hydroxy-pyrimidines their tautomeric compounds and their salts in intimate contact with a lightsensitive'silver halide gelatine emulsion.

2. A photographic material having a fog inhibiting compound selected from the group consisting of 2-amino-4-hydroxy-pyrimidine, the alkyl, aryl, aralkyl and arylene substituted 2-amino-4- hydroxy-pyrimidines their tautomeric compounds and their salts incorporated in'a light sensitive silver halide gelatine emulsion.

3. A photographic emulsion comprising a silver halide gelatine emulsion having incorporated therein as a. fog inhibiting agent, a small proportion of benzoylene guanldine.

6. A photographic material having a fog inhib-- iting compound selected from the group consisting of-2-amino-4-hydroxy pyrimidine, the alkyl, aryl, aralkyl and arylene substituted 2-amino-4- hydroxy pyrimidines, their tautomeric compounds, and their salts-in fog inhibiting relationship with a light sensitive gelatine silver halide emulsion.

JOHN DAVID KENDAIL. 1 

